Besides the aforementioned function in ion and water homeostasis, AQP4 has also been demonstrated to be involved in a number of acute and chronic cerebral pathologies such as the development of neuromyelitis optica, amyotrophic lateral sclerosis (ALS), Alzheimer’s disease, Parkinson’s disease and autoimmune neurodegenerative diseases [25–28]. The gene discussed is AQP4; the disease is neuromyelitis optica.